KVM: arm/arm64: timer: Check for properly initialized timer on init

When the arch timer code fails to initialize (for example because the memory mapped timer doesn't work, which is currently seen with the AEM model), then KVM just continues happily with a final result that KVM eventually does a NULL pointer dereference of the uninitialized cycle counter. Check directly for this in the init path and give the user a reasonable error in this case. Cc: Shih-Wei Li <[email protected]> Signed-off-by: Christoffer Dall <[email protected]> Signed-off-by: Marc Zyngier <[email protected]>
mrcsosa · Dec 9, 2016 · 8e1a047 · 8e1a047
1 parent 266068e
commit 8e1a047
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
@@ -425,6 +425,11 @@ int kvm_timer_hyp_init(void)
 	info = arch_timer_get_kvm_info();
 	timecounter = &info->timecounter;
 
+	if (!timecounter->cc) {
+		kvm_err("kvm_arch_timer: uninitialized timecounter\n");
+		return -ENODEV;
+	}
+
 	if (info->virtual_irq <= 0) {
 		kvm_err("kvm_arch_timer: invalid virtual timer IRQ: %d\n",
 			info->virtual_irq);